In numerous applications where endless power transmission devices are employed it is often desirable or necessary to control the tension in such devices during movement thereof around associated sheaves, pulleys, sprockets or the like, to assure optimum operating efficiency.
For example, in the automobile industry where a single endless power transmission belt is used to drive various automobile accessories, a belt tensioning device is required to assure satisfactory performance of the accessories as well as assure satisfactory service life of the belt.
Numerous tensioning devices such as belt tensioning devices have been proposed heretofore and most of these devices employ metal spring devices, hydraulic devices, or pneumatic devices to provide the tensioning action whereby such devices are comparatively complicated and expensive and require considerable maintenance. Accordingly, there is a need for a simple and inexpensive tensioning apparatus capable of providing reliable performance over an extended service life.